1. Technical Field
This invention relates qenerally to workpiece holders and, more particularly, to a method and apparatus for supporting and positioning of a workpiece for use in an inspection system incorporating an inspection probe.
2. Discussion
To use an inspection system to measure a workpiece it is highly beneficial and, for the most part, a requirement that the workpiece being inspected is positioned in a high precision inspection configuration and maintained in that position.
The conventional workpiece holder for an inspection system generally uses a single type of positioning device at a variety of locations on the workpiece. Moreover, the positioning devices are usually specially made for a specific workpiece and cannot be used for other workpieces. In other words, conventional workpiece positioning and holding devices lacked universality in that a single set of positioning devices could not be used for virtually any shape or size of workpiece.
U.S. Pat. No. 4,641,819 to Poland discloses a jig assembly for holding a variety of workpieces for assembly or machining processes. Individual workpiece positioners are permanently attached to a base portion in a matrix configuration. Each positioner can be raised or lowered, and can reach points within a certain range by rotating a tip around three axes A, B and C. It appears that the workpiece rests on a supporting ledge adjacent the tip. This patent suffers the drawbacks of not being truly universal. Further, one axis cannot be adjusted without affecting the other two.
U.S. Pat. No. 3,681,834 to Seidenfaden discloses a fixing and tensioning system for workpieces to be mechanically processed. A template is used over a platform having a uniform rectangular grid. The template indicates the positions for modular units for supporting different workpieces. The modular units are not adjustable on three axes to provide true universality of the system.
British Patent No. 764,351 discloses a jig assembly for supporting motor vehicle body shells of differing sizes. A series of location units are arranged on a platform having a number of places for securing the units. The units can be moved to other locations on the platform to support other sized vehicle frames. The location units do not appear to be adjustable.
Another workpiece support and positioning device manufactured by the Milford Fabricating Company, a division of the assignee of this invention, is known in the art. This device comprises a plurality of individual support elements positionable at different locations on a platform.
This invention eliminates the above-described problems as well as many others. Up until now a truly universal workpiece positioning and supporting system was not known. This invention enables ease of change from one workpiece to another using the same set of holding and positioning devices.